1. Field of the Invention
The present invention relates to organic light-emitting display (OLED) devices and, more particularly, to a transparent organic light-emitting display device.
2. Description of the Related Art
Applications of organic light-emitting display devices range from personal portable devices such as MP3 players and mobile phones to television sets owing to having superior characteristics such as wide viewing angles, high contrast ratios, short response times, and low amounts of power consumption.
An organic light-emitting display device has self-light emitting characteristics, and the weight and thickness of the organic light-emitting display device can be reduced since the organic light-emitting display device does not require an additional light source, unlike a liquid crystal display device.
Also, an organic light-emitting display device can be formed to be a transparent display device by having transparent thin film transistors and transparent organic light-emitting devices.
However, when such a transparent display device is in an off-state, image from an object positioned on a side of the transparent display device opposite to a user may be transmitted to the user through not only patterns of organic light-emitting devices, thin film transistors, and other conductive lines but also through the spaces therebetween. However, in the case of even the transparent display device, since the transmittances of the organic light-emitting device, the thin film transistor, and the other conductive lines are not high and the spaces therebetween are very small, the overall transmittance of the transparent display device is accordingly not high.
Also, the image may appear distorted, caused by the patterns of the organic light-emitting device, the thin film transistor, and the conductive lines. The reason for this is because the gaps between the patterns are only a few nanometers, that is, at a level almost close to the wavelengths of visible light, and thus, the gaps scatter light therethrough.
Furthermore, if an opposite electrode commonly formed over a screen of the transparent display device is formed to a thin thickness so as to improve the transmittance of external light, then a voltage drop, i.e., so called an IR drop, may occur in the opposite electrode. In particular, as organic light-emitting display devices become larger, this phenomenon may become more serious.